It's hard to say what's causing the 502 with the given information. If you
cf login as an admin user, target the
system org and
p-spring-cloud-services space you'll see the SCS broker & broker-worker applications. Run
cf logs on both applications, then try provisioning a new SCS service. This should result in dumping some error messages from one of the two applications, and the errors will provide details about what is wrong.
The common causes of a 502 are listed here: http://docs.pivotal.io/spring-cloud-services/prerequisites.html
Hope that helps!